1. Field of the Invention
The present invention relates to a magnetoresistive film including: a pinned ferromagnetic layer; a free ferromagnetic layer; an intermediate layer interposed between the pinned and free ferromagnetic layers; and a pinning layer, such as an antiferromagnetic layer, contacting the pinned ferromagnetic layer.
2. Description of the Prior Art
A magnetoresistive element is in general used to read out information data from a magnetic recording disk in a magnetic recording medium drive or storage device such as a hard disk drive (HDD). A magnetoresistive film such as a spin valve film is utilized in the magnetoresistive element, for example. The electric resistance of the spin valve film varies in response to the rotation of the magnetization in the free ferromagnetic layer. Such variation in the electric resistance enables discrimination of magnetic bit data on the magnetic recording disk.
In general, the free ferromagnetic layer of the spin valve film includes a nickel iron (NiFe) alloy layer and a cobalt iron (CoFe) alloy layer superposed on the nickel iron alloy layer. The nickel iron alloy layer is supposed to contribute to establishment of the uniaxial magnetic anisotropy in the cobalt iron alloy layer. The establishment of the uniaxial magnetic anisotropy leads to a reliable rotation of the magnetization in the free ferromagnetic layer which receives a magnetic field from the magnetic recording disk. A reliable discrimination of magnetic bit data can be achieved in this manner.
A higher density of the magnetic recordation may require a further enhanced output of the magnetoresistive element. The output of the magneto resistive element depends upon the thickness of the free ferromagnetic layer, for example. A reduced thickness of the free ferromagnetic layer is supposed to enhance the output of the magnetoresistive element as required. However, if the thickness of the nickel iron alloy layer is reduced in the free ferromagnetic layer, the uniaxial anisotropy is hardly established in the free ferromagnetic layer. Loss of the uniaxial anisotropy tends to hinder a reliable discrimination of magnetic bit data.